Control apparatus



Nov. 23, 1948. BMK 7 2,454,588

conmoz. APPARATUS F11 April 23, 1943 a sheets-sheet 1 lhmentor Nov. 23, 1948. A. E. BAAK comnou APPARATUS 3 Sheets-Sheet 2 Filed April 23. 1943 attorney Nov. 23, 1948., A. E. BAAK coma o1; APPARATUS I5 Sheets-Sheet 3 Filed April 23, 1.943

ON. mm 38 mwntEB $R DRE:

3nventor #156777 1 fill/7K Qitorncg Patented Nov. 23,

UNITED STATES, PATENT OFFICE Albert E. Baak,

Minneapolis, Minn.,

ratus, and particularly to control apparatus of Los Angeles, Calif.. assignor to Minneapolis-Honeywell Regulat or Company,

a corporation of Delaware the type wherein a motor driven deviceis positioned in accordance with the resultant of a plurality of controlling conditions. While my inventlon is of particular utility when used in a system for controlling the pressure of the air supplied to the intake manifold of an internal combustion engine, as disclosed in the present specification, it will be readily understood that my invention is capable of many other applications, and that its utility is not limited to this particular system. I

Internal combustion engines used on aircraft are sometimes provided with a compressor,

usually termed a supercharger, which is driven by a turbine powered by the exhaust gases of the engine. The speed of the turbine, and hence the compression ratio of the compressor, is controlled by a device termed a waste gate, which is a valve or damper that by-passes part of the exhaust gases from the exhaust manifold directly to the atmosphere instead of directing them through the turbine. In order to secure optimum operating conditions for the engine. it is usually dosirable to maintain the intake manifold pressure of the engine at a substantially constant value. The intake manifold pressure'may be varied either by adjusting the position of thethrottle or by adjusting the position of the waste gate associated with the turbine which drives the supercharger.

In the co-pending application oi Hubert T. Sparrow and Albert E. Baak, Serial No. 476,798, filed February 22, 1943, there is disclosed asystem for controlling the waste gate of a turbine the resultant of a Application Apr-i123, 1943, Serial No. 484,226

8-Claim|. (Cl. 280-5) 2 the pressure-of the air discharged by the supercharger and a second control effect dependent upon the rate of change of the pressure in the exhaust manifold.

Another object of this invention is to provide an improved electrical control system in which a single controller is operated in accordance with plurality of controlling conditions. L

A further object of the present invention is to provide an improved control device, of the type in which a control element is operated in accordance with the resultant of a plurality of variable control forces. I

A further object of the present invention is to provide a control device in which two pairs or bellows act in parallel on a beam, and a lever moved by the beam operates a control device.

Another object of the present invention is to provide a control device of the type described, wherein one of the two pairs of bellows produces a force variable in accordance with the changes in an absolute pressure condition, and the other pair of bellows produces a force varying with the rate or change of a second pressure condition.

Another object of the present invention is to provide improved means for controlling the flexibility of a mechanical system including a plurality of flexible bellows, in order to control the differential between the forces required to hold the system in two different positions.

Another object of the present invention is to provide an improved and more compact control device in which a single control element is positioned in accordance with the resultant of a plurality of controlling conditions.

driven supercharger in accordance with the pressure of the air discharged by the supercharger. In that system, an electrical motor drives the waste gate, and this motor is controlled in accordance with the unbalance of an electrical network which includes two variable impedance devices.

. One of these variable impedance devices is op- Other objects and advantages of my invention will become apparent from a consideration of the appended specification, claims and drawing, in which Figure 1 is an elevational view of a. control device embodying certain features of my invention.

Figure 2 is a sectional view taken along the lines 2-2 of Figure 1, looking in the direction of the arrows, with some of the parts removed for the sake of clarity,

Figure 3 is an elevational view of the right end of the structure shown in Figure 1,

Figure 4 is a plan view of the device shown in Figure 1 with the top of the casing removed,

Figure 5 is a detail sectional view taken along the line 55 of Figure 4, looking in the direction of the arrows,

Figure 6 is a sectional view taken along the line 3-3 of Figure 3, and looking in the direction of the arrows.

Figure 'l is a view of a detail of the device shown in Fi ure 1,

Figure 8 is a view showing the details of the mounting of the bellows in the device shown in Figure 1, and, I

Figure 9 is a somewhat diagrammatic illustration of the control device of Figure 1 applied to a system for controlling the pressure of the air.

. other suitable means to the top plate i as indicated in Figure 1. The bellows 3 and 3 likewise have provided respectively end members H and I2 which are similarly fastened to the bottom plate 2.

Positioned intermediate the bellows 3 and'1 and the bellows 3 and 3 is. a beam or plate i3 havingupturned ears i4 and i3 provided at opposite ends thereof. The bellows 3 and 3 are secured to the plate l3 by a fastening member I3, while the bellows 1 and 3 are secured to the plate l3 by a fastening member 11 as shown in Figure 8. Pins i3 and I3 project outwardly from the upturned ears i4 and I3, respectively, as best shown in Figure 4. The lower surface of each of these pins is tapered to form a knife edge. These knife edges cooperate with similarly tapered notches in the upper surfaces of the extremities of the arms 2i and '22 of a U-shaped lever 23. Pins 23 and 24 are fixedly mounted on the end plates 3 and 4, respectively, and project inwardly therefrom. The upper surfaces of the pins 23 and 24 are tapered to form knife edges, and these knife edges cooperate with tapered notches 23 in the lower edges of the arms 2! and 22. The pin 24 and its cooperating notch 23 are shownin detail in Figure 5. The lever 23 is biased for movement in a clockwise direction around the pivot pins 23 and 24 by a tension spring 23 fastened to the lever 23 at 23, as shown in Figure 2.

The opposite end of the spring 23 is secured to a threaded nut 33 which may be adjustably.

positioned for varying the tension of the spring by an adjustment screw 3i. Thus the arms 2i and 22are held in engaging relation with the pins i3 and i3 respectively by the tension of the spring 23.

A plate 32 is carried by the arm 23. Affixed at the top of the supporting plate I and projecting downwardly therefrom is a screw 33 carrying stop nuts 34 and 33 which limit the movement of the plate 32 and thereby the movement of the lever 23.

Fastened at one edge of the plate 32 by a screw 33 is one end of a metal tape 31. Tape 31 extends around a roller 43 and is attached to the roller 43 by a pin 4| (see Fig. 7). The tape 31 has a wide portion extending downwardly, as viewed in Figures 1 and 7, from the roller 43.

cured to an insulating sleeve 42a which in turn projects through the end plate 4 and has mounted at the outer end thereof a potentiometer arm 43 which is arranged for adjustment along a suitable resistance 43 "mounted on brackets 41 and 43 as shown in Figure 3. The purpose of this resistance will be explained hereinafter. v i

A fixed bracket 44 has a pivot; screw 42b threaded therein and locked in position by a nut 42c The end screw 42b is pointed and extends into the cone shaped end of shaft 42 so as to act as a low friction pivot or bearing for the right end of such shaft.

Positioned at the opposite end of the shaft 42 is a spring blade 43 fixed at one end to the bracket 43 and biased so that its free end bears against the pointed left end of the shaft 42 so as to provide a low friction bearing. The bias or tension of spring blade 43 holds the right end of shaft 42 on the pointed end of screw 42b. Further, if it is desired to increase or decrease the tension between potentiometer arm 43 and resistance 43 it is only necessary to loosen locknut 42c and turn screw 42b in or out. The tension of spring blade 43 will permit such axial movement of rod 42. Also, as indicated above,

such axial movement is permitted between roller 43 and the squared portion of shaft 42.

The lower end of the metal tape 31 previously described is fastened to a ring 33 which operably engages a hook 3! at the end of a lever 32 as shown in Figure 2. The lever 32 is pivoted on a pin 33 mounted on a pair of brackets 34 projecting upwardly from the bottom plate 2. A spring 33 is fastened at the other end 33b of the lever 32 in such a manner as to-tend to bias the lever 32 in a clockwise direction about the pin 33 as shown in Figure 2. The spring 33 is adjustably fastened at one end to a nut 33a, carried by a screw 33. The position of nut 33a, and hence the tension in spring 33. may be adjusted by rotating screw 33. It will thus be seen that the spring 33 exerts a biasing force upon the lever 32 tending to move the tape 31 downwardly so 'as to rotate the roller 43 as viewed in Figure 2 in a clockwise direction and to move the lever 23 in a similar direction about the pivot 24. Thus it will be seen that both the biasing springs 23 and 33 tend to move the lever 23 about the pins 23 and 24 in a clockwise direction, while the spring 33 also functions to maintain the tape 31 under tension. I

As indicated in Figures 1 and 8, suitable passages are provided, designated by the numerals 31 and 33, for connection of the interior of the pressure responsive bellows 3 and 3, respectively, to suitable pressure sources, as will be explained.

The bellows 3 is connected through the passage 31 to a source of pressure, which may be, as hereinafter illustrated in connection with Figure 9,

the pressure of the air discharged by the com- This wide portion is slotted to permit the passage pressor in the air induction system of an internal combustion engine. The purpose of bellows 3 is to compensate the bellows for variations in at- -or substantially so, and

mospheric pressure. To this end it is evacuated. is internally provided with a spring Ia. This sprin exerts sufllcient force downwardly on lever 20 to hold it against its various pivots at all times. Changes in atmospheric pressure will equally affect the exteriors of each of bellows I and I and therefore balance each other out. I

Since the effects ofatmospheric pressure on the bellows I and I cancel each other. the net force producedby the bellows I and O on the beam I3 is a force which is a measure of the absolute pressure within the bellows I.

- 6 deflect the bellows from The bellows I and I cooperate to produce a a force on'the beam II which is a measure of the change of the pressure transmitted through the passage It to the interior of bellows I. 'As illustrated hereinafter in Figure 9. the passage 68 may be connected to the exhaust manifold of an internal combustion engine. The interior oi bellows l is provided with a spring in.

The exteriors of both bellows I and 8 are exposed to atmospheric pressure, so that the eifect oi atmospheric pressure on these two bellows cancels each other out. The interiors of the bellows l and I are connected through an orifice Win the fastening member H by which the two bellows are attached to the" beam I4. 4 needle valve. 82 carried by the fastening member i'l regulates the size of the orifice ill. The needle valve 62 may be adjusted by a screw 08 which may be reached by removing a plug II in the member and which closes the upper end of the bellows 'l. v

The orifice lt'gdelays the equalization of the pressures within the bellows I and}. If the pressure supplied to the bellows I changes gradually, the orifice it permits the passage of iiuid. sumrate of their normal position. This arrangement is best shown in Figure 2. There may be seen a bell-crank lever Oil, pivotally mounted on a pin I carried by the bracket It. A tension spring 02 is connected between one end of the lever and a nut '4 carried by a screw Ila which passes through the plate I. The opposite end of lever 00 carries an abutment 86 which is recessed for engagement by one end of a pin 68. The opposite end of pin "is engaged in a similar recess iormed in an abutment 10 attached to the lever 20 by a rivet ii.

- When the points of contact between the pin 68 and the abutments It and" are aligned with the pin on which the lever 20 is pivoted, it will be seen that the tension of the spring '2 is opposed by a reaction force at the pin 24 extending in the direction of the lever 20. The tension of spring 02 does not then tend to rotate the lever 20 about its pivot 24.

As soon as the lever 20 moves upwardly or downwardly from theposition shown in the drawing. under the influence of the bellows I, I, 1 and 8, the ends of the pin at are no longer aligned with the .pivot pm It on which the lever 20 rotates. The spring 82 then exerts, through the pin II. a force tending to move the lever 20 further away from the neutral position shown in the cient to allow the pressure within the bellows I to follow the variations in pressure within the bellows 8 Upon; a sudden increase or decrease in pressure in the bellows 8 however, the fluid flow through the orifice 59 is not sufliciently rapid to equalize the pressures, and a pressure differential then exists between the interior of bellows i and the interior of bellows 8. This diiferential pressure causesai-force to be exerted on the beam it, which force is ;a measure of the rate of change of the pressure inside the bellows I. If the pressure inside the bellows 8 is increasing, the force on the beam it acts upwardly, but if the pressure inside the bellows 8 decreases. the force on the beam it acts do nwardly.

Although in il ustrating the invention, I have shown an arrangement wherein the bellows 6 and t are connected'to two diilerent sources of pressure, it will be readily apparent that this mode of operation of my device is not necessary to my invention, but that both bellows B and 8 may be connected to the same source of pressure, where that mode of operation is desirable.

In my device, there are four resilient bellows, each of which has an appreciable spring rate.

drawing. Therefore, the force required to move the lever 20 away from the neutral position in either direction is reduced, and the distance through which the lever is moved by a given force may be regulated by adjusting the tension in the spring 62. The distance through which the lever 20 and hence the slider 45 is moved by a given force supplied to the beam it may be termed the differential of the control instrument, and the screw may be termed a difl'erential adjusting screw. The reason for this terminology is that for any two given positions of the slider 46, there exists a definite diil'erential between the forces producedby the bellows which cause the slider .46 to assume those two positions. By changing the tensionin the spring 02, this force differential may be adjusted.

Referring now to Figure 9. there is shown an internal combustion engine it with an air induction and exhaust system, and a control system utilizing a device of the type disclosed in Figures 1 to 8, inclusive, to control the pressure of the air supplied to the intake manifold of the engine.

In the arrangement disclosed in Figure 9, air for supporting combustion in the engine 16 passes through an inlet 13 to a. compressor or supercharger 12, whence it is discharged through a duct Ii into an aftercooler 14. The aftercooler i4 is provided to reduce the temperature of the compressed air, which is considerably increased because of the heat of compression. The air then passes through the carburetor 8i, and intake manifold 82 to the engine 16. From the engine II, the exhaust gases pass through an exhaust The term spring rate may be defined as the ratio between the force exerted on a flexible member to displace it from the position it tends to assume normally and the distance through which the flexible member is displaced by that force. Be-

cause of the use of four bellows in my device,

it may be seen that the movable mechanical system of my device opposes a rather stiff resistance to a force tending to cause a movement thereof.

In order to provide a more resilient system, I have provided means for compensating the spring rate on the four bellows. In other words, I have provided means which aids the force tending to manifold II, andthence either directly to the atmosphere through a waste gate or through a turbine 11.

A throttle 83 in the carburetor Il may be positioned by means of a lever,l Ill, of suitable construction. The waste gate 80 is positioned by a motor" acting through a link lill. Power is supplied to control the motor 81 from an amplifier and power supply unit II, which is disclosed in more detail in the co-pending Sparrow and Baak application previously mentioned. The amplifier M has a. pair of input terminals 85 and I8, and

servesto cause operation of motor I! in one diaccuse 7' rection or the other, depending upon the phase of an alternating signal applied to the signal input terminals 85 and 8B.

sliding contact 45 is moved in accordance with the resultant of the various pressure conditions acting on the bellows I, 6, 1 and 8. The network 8| also includes a resistance 95 along which a slider 98 is moved by the waste gate motor 81. The interior or bellows 8 is connected through a conduit III to the duct II, so that the bellows 8 responds to the pressure of the air discharged by the supercharger I2. The interior of bellows 8 is connected by a conduit It to the exhaust manifold 15, so that the bellows I and 8 move the beam It in accordance with the rate of change of the exhaust pressure.

The mechanism by which the bellows 5. O. 1 and 8 move the slider 45 is shown very schematically in Figure 9, for the sakeoi simplification.

If the pressure in the conduit I decreases, the slider 45 is moved in a counter-clockwise direction, or upwardly along the resistance 48, and the network BI is unbalanced in adirection so that overshooting or hunting condition. For example, it the pressure in the duct II decreases, thereby resulting in a counter-clockwise movement of slider 45, the waste gate is moved towards closed position by the control system. As soon as the waste gate moves towards closed position, the

pressure or the exhaust gases increases rapidly,

thereby causing the bellows I. and 8 to exert an upward force on the beam I3, tending to bring the slider 45 back to its original position. The motion'of the waste gate is thereby slowed down and stopped before the pressure in the duct II has been restored to the value which the system is set to maintain; As the force produced by the bellows 1 and 8 slowly dies away due to the equalization of their internal pressures through the orilice between these two bellows, the turbine and supercharger are accelerated by the increased pressure in the exhaust manifold and the pressure in the duct II is restored to the value it is desired to maintain. The slowly increasing force I produced by the bellows 6 opposes the slow dethe phase of the potential impressed on amplifier input terminals 86 and 88 causes motor 81 to drive the waste gate 80 towards closed position. This increases the proportion of the exhaust gases which are directedthrough the turbine, thereby increasing the turbine speed and hence increasing the compression ratio of the supercharger and changing the discharge pressure of the supercharger back toward its original value. If. on the other hand, the discharge pressure of the 81113617 charger increases, the slider 45 is moved clockwise, or downwardly along resistance 48, thereby unbalancing the network 9| in a direction so'that the motor 91 moves the waste gate 80 toward open position thereby reducing the speed of the turbine I1 and the supercharger I3, and restoring the pressure in the discharge of the supercharger to its original value.

Because of the inherentlag in the system between the exhaust manifold I5 and the conduit 'II to which the interior of bellows B is connected, it is desirable to utilize the rate of change of the pressure in the exhaust manifold so as to obtain a compensating or anticipating effect in the control system. In other words, there is quite a time delay between a change in the position of the waste gate 80 and the time when the pressure in the duct ll reaches a substantially constant value corresponding to the new position of the waste gate 80. 'This tlmedelay is due to the time required to accelerate the supercharger. If means were not provided to compensate the system for this time delay, the bellows 6 would continue to call for increased pressure from the compressor 12 at a time when the waste gate 80 had already reached a position which would eventually cause the supercharger discharge pressure to assume the required value. This would result in an overshooting of the waste gate, to a position beyond that which would cause the compressor discharge pressure to reach the desired value, and the com-' pressor discharge pressure would then continuously hunt about the desired value, first increasing and then decreasing with respect to that value without ever remaining substantially constant. The use of the bellows I and 8 to compensate the system for the rate of chanBe of the exhaust pressure prevents the establishment of such an crease in the force produced by the bellows I and 8. and the system becomes balanced again. An analogous operation takes place upon an increase in the pressure in the duct II.

The control point of the network 8|, or in other words the value of pressure in the duct II which the system will automatically maintain, may be adjusted by suitable means in the network 0|, such as is disclosed in the copending Sparrow and Bank application previously referred to.

While I have shown and described a preferred embodiment of my invention, other modifications thereof will occur to those skilled in the art, and

' I therefore wish my invention to be limited only by the appended claims.

I claim as my invention:

1. A device of the character described, comprising, in combination, a pivotally mounted U- shaped lever, actuating means for moving said U-shaped lever, a pivotally mounted second lever. a connecting pin pivotally mounted between said U-shaped lever and said second lever, biasing means for pivoting said second lever so as to hold said pin in engaging relation with said U-shaped lever and said second lever, whereby upon positioning said U-shaped lever in a predetermined neutral position in relation to said pin said biasing means has no biasing effect upon said U-shaped lever. but when said U-shaped lever is pivotally.

means operatively connected to said U-shaped I lever and positioned thereby. I

2. A device of the character described, comprising, in combination, a pair of supporting members, a first pair of bellows mounted between said supporting members, a second pair of bellows mounted between said supporting members, a' movable plate positioned intermediate the bellows of each of said pairs of bellows, pressure connections whereby each of said pairs of bellows may be actuated in response to pressure conditions, a U-shaped lever spanning said plate and having arms operatively engaging the opposite ends of said plate whereby said lever may be actuated upon movement of'said plate by said pairs of bellows in response to said pressure conditions, said lever being pivoted adjacent the points of engagementof said arms with said plate so as to re- 9 strain tilting of said plate, and means actuated by said lever upon movement thereof.

3. Control apparatus, comprising in combination, control means to be operated in accordance with the resultant of a plurality of variable conditions, a U-shaped lever for operating said control means, a translatable beam spanning said shaft, means responsive to said variable condition for rotating said lever about said axis, a second lever rotatable about another axis parallel to said shaft, a flexible tape fastened to said'flrst and second levers and passing over said pulley, and spring means extending between said second lever and one of said plates for maintaining said tape under tension.

' 5. Electrical apparatus for controlling the pres-, sure of the air supplied to the intake manifold of an internal combustion engine provided with a compressor driven bya turbine powered with exhaust gases from said engine, comprising in combination, means for controlling the compression ratio of said compressor, electrical motor means for driving said compression ratio controlling means, means including an electrical impedance network for controlling said motor means, variable impedance means connected in said network, said network being effective to control said motor in accordance with the variations of said impedance, means responsive to the pressure of the air discharged bysaid compressor for producing a force varying in magnitude with said pressure, means responsive to the rate of change of the pressure of said exhaust gases for producing a force varying in magnitude with said rate, and

mechanical means for combining said forces to,

produce a resultant force and to vary said impedance means proportional to said resultant force. 6. Electrical apparatus for controlling the pressure of the air supplied to the intake manifold of an internal combustion engine provided with a compressor driven by a turbine powered with exhaust gases from said'engine, comprising in com- ,bination, means for controlling the compression ratio, of said compressor, electrical motor means for driving said compression ratio controlling means, a normally balanced electrical network, first variable-impedance means connected in said network, means responsive to the pressure of the air discharged by said compressor for producing a force varying in magnitude with said ,pressure, meansv responsive to the rate of change of the pressure of said exhaust gases for producing a force varying in magnitude with said rate, mechanical means for combining said forces to produce a resultant force and to vary said first impedance means in accordance with said resultant force, said first impedance means being effective I upon variation thereof to unbalance said network,

means responsive to unbalance of said network for controlling said motor means and second variable 10 impedance means operated by said motor means for rebalancing said network.

7. A device of the character described comprising, in combination, support means, a, relatively long translatable beam, two force exerting means for applying parallel forces to said beam at longitudinally spaced points thereon, each said force exerting means including a pair of devices engaging said support means and acting in opposition to each other on said beam, at least one device of each pair being a bellows responsive to a pressure condition, and means for causing the movement of said beam produced by a variation in the forces exerted by said force exerting means to 1! always take place only in a, direction parallel to the direction of said forcessaid last named means comprising a rigid lever pivotally connected to said beam at two longitudinally spaced points of the latter and pivotally mounted to said support means in such a manner as to prevent pivotal movement of the beam about its transverse axis perpendicular to the direction of said force.

8. Electrical apparatus for controlling the pressure of the air supplied to the intake manifold of an engine having a combustion chamber and provided with a turbosupercharger powered withexhaust gases from said combustion chamber comprising in combination; means for controlling the compression ratio or said turbosupercharger, elec trical motor means for driving said compression ratio controlling means, a balanceable electrical impedance network, a variable impedance means connected in said network, said network being the extent and direction of unbalance of the network, means responsive to a pressure appurtenant to an operating condition of the turbosupercharger for producing a force varying in magnitude with said pressure, means responsive to the rate of change of a pressure appurtenant to an operating condition of the turbosupercharger for producing a force varying in magnitude with said rate, mechanical means for combining said forces to produce a resultant force and to vary said impedance means in accordance with said resultant force, and follow up means driven by said motor for rebalancing said impedance network.

'- ALBERT E. BAAK REFERENCES CITED UNITED STATES PATENTS Number Name Date 766,820 Fulton Aug, 9, 1904 I 1,091,044 Delzell Mar. 24, 1914 1,186,180 Fulton June 6, 1916 1,459,218 Knaak June 19, 1923 00 1,998,136 Jaenichen et al. Apr. 16, 1935 2,005,773 De Florez June 25, 1935 2,027,275 Foster Jan. 7, 1936 2,030,386 Miller Feb. 11, 1936 2,149,216 Gravley Feb. 28, 1939 2,274,254 Newton Feb. 24, 1942 r 2,285,540 Stein Jun 9, 1942 2,358,363 I Truesdeii Sept. 19, 1944 2,374,708 Shoults -1 May 1, 1945 FOREIGN PATENT-{'5 'Number Country Date 434,289 Great Britain Aug, 29, 1935 effective to control said motor in accordance with 

